A method for determining a switching state of a valve that is actuated by a coil, wherein the method includes: respectively ascertaining a current flowing through the coil and a voltage applied to the coil at several times which follow one another with a prespecified time interval, calculating an inductance variable of the coil based on the currents, the voltage and the time interval, and determining the switching state based on the inductance variable. Also disclosed is a solenoid valve assembly.

A method for determining a switching state of a valve, an inductance variable being determined on the basis of current and voltage measurements and the switching state being determined on the basis of the inductance variable. Also disclosed is a solenoid valve assembly for carrying out such a method.

There is a solenoid including a stator having a first stator tooth and a second stator tooth, and an armature having a first armature tooth and a second armature tooth. The armature is moveable with respect to the stator over a predetermined stroke. A coil is associated with one of the stator and the armature for conducting an electric current and generating magnetic flux that is guided by the stator and the armature. The stator or the armature acts as a ferromagnetic core for the coil. There is a first air-gap between the first stator tooth and the first armature tooth that has a first length, and a second air-gap between the second stator tooth and the second armature tooth that has a second length. The first and second lengths are constant to within a predetermined margin over the predetermined stroke when the first and second armature teeth overlap the first and second stator teeth respectively.

A bistable electromagnetic actuator is described. The actuator includes a mobile assembly and a fixed assembly. The mobile assembly includes at least one pair of ferromagnetic plunger-cores, a frame integrally connecting the plunger-cores, and a guiding element. The fixed assembly includes a ferromagnetic core having cavities defined on each of its two sides configured to receive a corresponding one of the plunger-cores, at least one magnet positioned between the cavities in the core and being able to create a first magnetic flux, at least one coil operable via an excitation current to create a second magnetic flux, and a guiding element adapted to cooperate with the guiding element of the mobile assembly to allow the mobile assembly to move between a first and a second stable position. Methods for actuating the bistable electromagnetic actuator are also described.

A method for controlling a magnetic valve and particularly a method for dispensing and/or aspirating a volume of liquid as well as a corresponding dispenser/pipetting apparatus is disclosed. The method for controlling a magnetic valve has measuring a capacitance at the magnetic valve and determining a position of a plunger based on the measured capacitance. The method for dispensing or aspirating a volume of liquid has controlling a flow of a system fluid by a magnetic valve located between a pressure source and a dispenser/pipetting tip, dispensing or aspirating a volume of liquid through an exterior opening of the tip dependent on the flow of the system fluid, wherein controlling the flow and determining a flow time in dependence of the volume of liquid to be dispensed or aspirated, and controlling the magnetic valve is held open for the duration of the flow time.

The invention relates to an electromagnetic positioning device (10) having energizable stationary coil means (1), a magnetic guide element (2) associated thereto and having a core section (2a) and an anchor unit (3) moveable in relation to the guide element (2) and along an axial movement direction (L) as a reaction to an energization of the coil means (1), wherein the guide element (2) is a hollow cylinder that partially surrounds the anchor unit (3). The positioning device (10) has an ultra-wide-band sensor unit (4) which is preferably integrated in the guide element (3) and is designed for measuring the position and/or the displacement of the anchor unit (3) in the guide element (2).

Disclosed herein are reluctance actuators and methods for feedback control of their applied force. Embodiments of the reluctance actuators include an electromagnet positioned to deflect a metallic plate to provide a haptic output. The control of the force is provided without force sensors (sensorless control) by monitoring voltage and/or current (V/I) applied during an actuation. For a given intended force output, an electrical parameter value (flux, current, or other parameter) is read from a look up table (LUT). The LUT may store a present value of the inductance of the reluctance actuator. The feedback control may be a quasi-static control in which the LUT is updated after actuation based on the monitored V/I. The feedback control may be real-time, with a controller comparing an estimated electrical parameter value based on the measured V/I with the value from the LUT.

The invention relates to a device for controlling armature solenoid provided with a DC voltage source (14), at least one buffer capacitor (18), which is connected in parallel to the DC voltage source (14) and has a known capacitance (C), and a first switch (28), which is arranged between the DC voltage source (14) and the buffer capacitor (18). The exciter coil (16) and a second switch (30) arranged in series therewith are connected in parallel to the buffer capacitor (18). A control and evaluation unit (22), when the buffer capacitor (18) is charged, opens the first switch (28) and closes the second switch (30) in order to determine, on the basis of the measurement voltage (20), the frequency of the resonant circuit having the capacitance (C) of the buffer capacitor (18) and the inductance (L) of the armature solenoid (12). The inductance (L) of the armature solenoid (12) is determined on the basis of the frequency, and the air gap width (h) of the armature solenoid (12) is determined on the basis of the inductance. The PWM control signal with which the armature solenoid (12) is operable in order to generate a predefined force to be applied by the armature solenoid (12) is applied to the second switch (30) on the basis of a look-up table or a mathematical modelling of the electromagnetic behavior of the armature solenoid (12).

A system may include an armature configured to move between a first position that electrically couples the armature to a first contact and a second position that electrically couples the armature to a second contact. The system may also include a coil configured receive a current, such that the current conducting in the coil is configured to magnetize a core. The magnetized core may cause the armature to move from the first position to the second position. The system may also include a control system configured to detect a position of the armature based on an inductance of the coil.

A drive unit for a gate valve controls a flow rate of fluid passing through an opening in a valve seat by forward and backward moving a valve plate against the opening in the valve seat. This drive unit includes a shaft connected to the valve plate, a linear motor for driving the shaft and drive control means to control the drive of the linear motor. The linear motor has a plurality of coils for generating a magnetic field by electric current and a permanent magnet assembly to react to the magnetic field generated by the plurality of coils. The plurality of coils forms a stator while the permanent magnet assembly is connected to the shaft and displaced together with the shaft to form a mover to forward and backward move the valve plate. Each of the plurality of coils is connected to its own control circuit and the drive control means individually controls the current flowing through each of the plurality of coils via the control circuit. The drive control means may be provided with a linear encoder to detect the current position of the permanent magnet assembly.